Process of treating metals.



UNITED strA rns mammal OFFICE.

EMERY G. GILSON, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

PROCESS OF TREATING METALS.

No Drawing.

1 '0 all whom it may concern..-

Be it known that I, EMERY G. GILSON, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certaln new and useful Improvements in Processes of Treating Metals, of which the following is a specification. I

This invention relates to the art of coating or otherwise treating metals so as to protect. them against the ctlects of oxidation and other similar corrosive agcncles, and has for its object the production of a coating upon a metal normally subject to corrosive action or a condition within the metal such that itis capable of withstanding the oxidizing and corrosive influence without harmful effect.

This invention relates more specifically to the treatment of such metals as copper, iron and the like, which readily oxidize. It is well known that copper oxidizes very rapidly even at moderate temperatures. Iron, at a moderate temperature oxidizes slowly, if unprotected, but at a high temperature the oxidation is so rapid as to render its use almost prohibitive. In a prior application filed by Tycho Van Aller on October 4th, 1911, Serial Number 652,756, and assigned to the same assignee as my application, there is described and broadly claimed an oxidizable metal rendered inoxidizable by causing another metal, such as aluminum, to alloy with it at the surface, and the process whereby the result is accomplished. In the said application the process described consists in bringing aluminum powder into contact with the metal and heating to the proper temperature under conditions which prevent oxidation of the metal. The aluminum powder is thoroughly mixed with a certain percentage of other material, such as sal ammoniac and zinc, and the articles to be treated are placed in an oven and surrounded-by the powdered mixture. The oven is then completely closed and slowly rotated. A temperature of about 450 to 700 0., depending up on the particular mixture used, is maintained within the oven and the treatment continued for about two hours. One mixture which has. been found to produce good results is 70% aluminum, 23% sal ammoniac, 7% zinc. The said application also describes a mixture in which graphite is substituted for zinc, the

about 700 C.

particular mixture specified being aluminum, 30% graphite, 10% sal ammoniac. In this case the temperature is raised to After the metal has been taken out of the oven it is fired at a temperature from 700 to 800 (J. for about fifteen or twenty minutes.

\Vhile this process has proven to be very satisfactory in practice, I have found that the same result may be produced by substituting aluminum oxid for some of the aluminum powder. I have found that where this mixture is used, a chlorid is also desirable, although a very small percentage will be satisfactory. Ammonuim chlorid has been found very satisfactory for this purpose. I have also found that it is desirable to have the process take place in a non-oxidizing atmosphere such for instance as an atmosphere of hydrogen or nitrogen. In treating iron, for instance, one very satisfactory mixture is as follows: 49% aluminum oxid (alumina). 49% aluminum, 2% ammonium chlorid. The temperature in this case is from about 850 to 900 C. In the case of copper or the like, I may employ a larger percentage of aluminum oxid. For instance, the following mixture has been found very suitable: 88% aluminum oxid (alumina), 10% aluminum powder, 2% ammonium chlorid. In the case of copper a temperature of about 800 C. is maintained and brass requires a temperature of about 050 C. (as high as possible without melting). In any case the powders are thoroughly mixed and preferably a certain amount of pressure is to be placed upon the materials in the oven so as to keep the powder pressed down in close contact with the pieces that are to be treated. Hydrogen may be led into the oven in any wcll-kiiown manner and the treatment continues for a length of time dependent upon the particular articles treated. In the case of a copper electrode 19; in diameter and 4 long, a treatment for one hour produces very good results. The material can be used over and over so that the only loss of material is the amount taken up by the articles calorized. From time to time aluminum and ammonium chlorid should be added to keep the powder up to standard.

What I claim as new and desire to secure by Letters Patent of the United States, is: 1. The process of treating metals torender Specification of Letters Patent. Patented Ma 24, 1914. Application filed March 12, 1913. Serial No. 753,665.

them inoxidizable which consists in heating 1,oe1,057 I consists in heating the metal in a non-oxidizing atmosphere to a temperature from 600 to 900 0. depending upon the particular metal, in contactwith a powdered mixture of pure aluminum, alumlnum oxid and a chlorid.

In witness whereof, I have hereunto set 'my hand this 10th day of March, 1913.

EMERY G. GILSON.

W'itnesses BENJAMIN B. HULL, HELEN ORFORD. 

